Skip site navigation (1)Skip section navigation (2)
Date:      Fri, 17 Aug 2012 12:09:54 -0600
From:      Ian Lepore <freebsd@damnhippie.dyndns.org>
To:        John Baldwin <jhb@freebsd.org>
Cc:        svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org
Subject:   Re: svn commit: r239356 - head/sbin/dhclient
Message-ID:  <1345226994.27688.129.camel@revolution.hippie.lan>
In-Reply-To: <201208171331.10655.jhb@freebsd.org>
References:  <201208171553.q7HFrhuf090457@svn.freebsd.org> <1345222934.27688.110.camel@revolution.hippie.lan> <201208171331.10655.jhb@freebsd.org>

next in thread | previous in thread | raw e-mail | index | archive | help
On Fri, 2012-08-17 at 13:31 -0400, John Baldwin wrote:
> On Friday, August 17, 2012 1:02:14 pm Ian Lepore wrote:
> > On Fri, 2012-08-17 at 15:53 +0000, John Baldwin wrote:
> > > Author: jhb
> > > Date: Fri Aug 17 15:53:43 2012
> > > New Revision: 239356
> > > URL: http://svn.freebsd.org/changeset/base/239356
> > > 
> > > Log:
> > >   Fix dhclient to properly exit and teardown the configured lease when
> > >   link is lost.  devd will start a new dhclient instance when link is
> > >   restored.
> > >   
> > >   PR:		bin/166656
> > >   Submitted by:	Peter Jeremy (mostly)
> > >   Reviewed by:	brooks (earlier version from Peter)
> > >   MFC after:	1 month
> > > 
> > > Modified:
> > >   head/sbin/dhclient/dhclient.c
> > > 
> > > Modified: head/sbin/dhclient/dhclient.c
> > > ==============================================================================
> > > --- head/sbin/dhclient/dhclient.c	Fri Aug 17 14:22:56 2012	(r239355)
> > > +++ head/sbin/dhclient/dhclient.c	Fri Aug 17 15:53:43 2012	(r239356)
> > > @@ -278,6 +278,11 @@ routehandler(struct protocol *p)
> > >  			    ifi->name);
> > >  			goto die;
> > >  		}
> > > +		if (!interface_link_status(ifi->name)) {
> > > +			warning("Interface %s is down, dhclient exiting",
> > > +			    ifi->name);
> > > +			goto die;
> > > +		}
> > >  		break;
> > >  	case RTM_IFANNOUNCE:
> > >  		ifan = (struct if_announcemsghdr *)rtm;
> > > @@ -316,6 +321,8 @@ routehandler(struct protocol *p)
> > >  
> > >  die:
> > >  	script_init("FAIL", NULL);
> > > +	if (ifi->client->active)
> > > +		script_write_params("old_", ifi->client->active);
> > >  	if (ifi->client->alias)
> > >  		script_write_params("alias_", ifi->client->alias);
> > >  	script_go();
> > 
> > I think the attached patch should give the same result without needing
> > to create/destroy a socket to check the link status every time a routing
> > info message arrives.  I've actually had this patch in my head for
> > several years, I just hadn't gotten around to submitting it yet.
> 
> Hmm, OpenBSD does check that, but they also seem to verify it via SIOCGMEDIA
> as well.  Do we think this is as reliable?  In the kernel we only seem to
> honor this if the NIC explicitly supports the capability:
> 
> #define RT_LINK_IS_UP(ifp)	(!((ifp)->if_capabilities & IFCAP_LINKSTATE) \
> 				 || (ifp)->if_link_state == LINK_STATE_UP)
> 
> Also, I don't think routing info messages are all that common of an event are they?
> 

I actually don't know how common routing info messages are; the ways I
use freebsd don't include a lot of heavy network usage.

The IFCAP_LINKSTATE question is interesting.  The #define comment for it
says "the runtime link state is dynamic."  The RT_LINK_IS_UP() macro is
interesting too, in that it appears to assume that the link must be up
if it isn't dynamic.  I think that means the more-correct way than I
posted would be a test such as

  if (!RT_LINK_IS_UP(&ifm->ifm_data))

It looks like IFCAP_LINKSTATE is added to if_capabilities by
miibus_attach() and a few specific NIC drivers (presumably ones that
don't use standard MII attachements to their PHYs).

I would hope all that adds up to the concept that any network driver in
control of links that can come and go will either automatically do the
right thing by using the miibus code, or by using its own equivelent
code when mii isn't appropriate, or the driver is buggy.  Hopefully
there aren't any in the last category. :)

-- Ian





Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?1345226994.27688.129.camel>